It’s the traditional Christmas day event that every year draws ­thousands of fans eager to catch a glimpse of the Royal Family.

But yesterday’s church service at Sandringham was marked by concern for the Duke of Edinburgh who was last night still recovering in hospital after his emergency heart operation.

The Queen, spending her first Christmas without her husband by her side for 55 years, still managed a smile as she put on a brave face for the crowds during the walk to the event on her Norfolk estate.

Prince William and wife Kate – spending her first Christmas as a royal – were also among those who attended.

It was not clear when the 90-year-old duke will be released from Papworth hospital in Cambridgeshire.

But he is not expected to join his family for today’s traditional Boxing Day shoot, an event he loves.

However, Prince Charles tried to reassure well-wishers his dad was ok.

He chatted to Carmilla Fitt after the church service. The 71-year-old, from Dover, Kent, said: “Charles told me the duke is coming on.

“He is very well and in very good spirits. He said he’s very determined.”

The prince told others in the crowd Philip was “resilient”. He reassured student Millie Farmer, 17, from Cambridge, that his father was “very well” and “getting much better”.

Philip had a stent tube fitted to open up a blocked coronary artery on Friday after suffering chest pains.

A Buckingham Palace spokesman said: “The duke is in good spirits and will remain in hospital under observation for a short period.

“The Queen will continue to be briefed on his condition. We do not have details of a release date at this stage.”

Speaking outside the hospital, Palace spokeswoman Ailsa Anderson had said on Saturday: “The Duke of Edinburgh had a good night and is in good spirits but he is eager to leave.”

Prayers were said for Philip at the service at St Mary Magdalene Church, attended by 20 royals and believed to be the largest ­gathering ever at Christmas.

The rector of Sandringham, Reverend Jonathan Riviere said: “We pray for the Queen and the Royal Family. Especially today we pray for Prince Philip and his continued recovery.”

But the duke didn’t miss out entirely on a family Christmas. Later in the day his grown-up grandchildren – Princes William and Harry, ­Princesses ­Beatrice and Eugenie and Peter and Zara Phillips - drove the 60 miles to Papworth to visit.

They turned up in a convoy of cars at around 4.30pm.

William arrived driving a Range Rover with Peter and Zara his ­passengers, while Harry drove an Audi with Beatrice and Eugenie inside.

The grandchildren appeared to have changed into more casual outfits. Prince William was wearing a shirt and dark blue jumper and glasses, and Harry sported a shirt and zip-up top.

The party of young royals left around 45 minutes later. The, Queen and her children, who visited Philip on Christmas Eve, remained at Sandringham.

The party were flown from Sandringham to Papworth at 11am and spend 45 minutes by his bedside. Shortly afterwards Prince Charles and Camilla also drove up from Highgrove to see his father.

A spokeswoman said the Queen left ­“reassured, knowing he is in good spirits”.

The Queen and Philip have not spent Christmas apart since 1956 when he was on a voyage round the Commonwealth on the Royal Yacht Britannia. He sent a message to his wife over the radio.

In Philip’s absence, Charles and Camilla earlier led the walk into the church. They were followed by William, Kate and Harry, Prince Andrew and daughters Beatrice and Eugenie and Prince Edward and his family.

Princess Anne, daughter Zara and her husband Mike Tindall – also joining the royals for the first time – brought up the rear.

The Queen arrived by car. She was dressed in a lavender dress by Karl Ludwig and an Angela Kelly hat. Afterwards, crowds of 3,000 cheered softly when the family emerged into the winter sunshine.

Children queued to give flowers to the 85-year-old Queen and other royals.

Kate bent down to talk to Freedom Scott Tansley, nine, who had travelled from Turkey for the event.

The youngster said: “She was very kind and nice.” Sheila Clark, 54, from Glasgow, added: “I gave Kate an album I made of the wedding day. She told me it was such a lovely day. I also gave Camilla a card for the Duke of Edinburgh.”

Harry got the biggest cheer of the day when he kissed one girl on the cheek. When her friend asked for a peck too he replied with a grin: “I can’t give you a kiss, I just kissed her.”

Royal watcher Alison Goose said: “The family seemed in very good spirits and seem very upbeat about Philip’s recovery. He is resilient and I predict he will be back to normal in no time.”

Alison, who has been following the royal family for 25 years, revealed that she had not seen crowds of ­yesterday’s size at Sandringham since the days of Princess Diana.

She added: “I remember Diana first introduced William informally to the crowds here. It’s lovely to see William with Kate, guiding her and supporting her doing the same.”